Device for data transmission between vehicle sensors and a processor in a controller

ABSTRACT

A device for data transmission between vehicle sensors and a control unit, which is used to decode data telegrams having sensor data from the vehicle sensors and to reformat them into SPI (serial peripheral interface) data telegrams. Furthermore, an interface module of the control unit transmits the SPI data telegrams to the processor of the control unit. By using an alter bit, the processor determines whether to retrieve the newest sensor data or the preceding sensor data. The interface module converts the sensor data in each case into a 10-bit data field of an SPI data telegram, into which the interface module may supplement missing data. By counting out the edges, it is possible for the interface module to recognize the data telegrams from the sensors.

FIELD OF THE INVENTION

The present invention relates to a device for transmitting data betweenvehicle sensors and a processor of a control unit.

BACKGROUND INFORMATION

In conventional communication systems for transmitting data betweenvehicle sensors and a processor of a control unit, it is possible to usespecial data telegrams for transmitting data between a sensor and aprocessor in a control unit.

SUMMARY

A device according to an example embodiment of the present invention fortransmitting data between vehicle sensors and a processor for thecontrol unit includes an interface module that receives first datatelegrams from a plurality of vehicle sensors, captures the data fromthe first data telegrams, unformatted, and sends them on synchronouslyin second data telegrams to the processor within the control unit. It isthereby possible to let various sensors simultaneously transmit data tothe control unit in different formats for the individual data telegramsbetween the interface module and the sensors. Therefore, the deviceaccording to the present invention is extremely flexible and expandable.

According to one implementation, the data field of the second datatelegram is filled up with zeros, if, in the respective data telegramfrom the sensor, there is less data than the maximum level the datafield can accommodate. Thereby, advantageously, the same data telegramformat may be used for the processor. This leads to a simplifiedprocessing of the data.

In addition, according to an example embodiment of the presentinvention, a memory of the interface module may be included fortemporary storage of sensor data, so that a processor may retrieve oldor new sensor data. This is particularly advantageous when a sensorfails, and thus the preceding sensor data may still be available forfurther processing. This case may arise when there is a collision inwhich vehicle sensors that are situated peripherally in the vehicle aredamaged by the impact.

According to an example embodiment of the present invention. theinterface module receives the data telegrams from the vehicle sensors in13-bit data frames, and counts out the edges of the data frames in orderto recognize the data telegrams.

The vehicle sensors may be supplied with electrical energy by theinterface module. The data transmission can used for this by a currentmodulation of the direct current used for the energy supply. The currentmodulation is less sensitive with regard to EMV problems. Furthermore,Manchester coding may be used, so that only two different current levelsare used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the device according to an exampleembodiment of the present invention.

FIG. 2 is a flow chart of a method according to an example embodiment ofthe present invention.

FIG. 3 shows an example data telegram frame of a sensor.

FIG. 4 shows an example assignment of the data to an SPI data field.

FIG. 5 shows an example SPI data frame.

FIG. 6 shows an example SPI line.

DETAILED DESCRIPTION

Because of the increasing integration of ever more sensors into a motorvehicle, which are used for sensing a vehicle crash, it is useful toallow for future sensors having new data telegrams to transmit data tothe processor of a control unit that is already installed. To accomplishthis, an interface module is provided according to the present inventionwhich receives the individual data telegrams from the vehicle sensorsand reformats the data into SPI (serial peripheral interface) datatelegrams and then transmits them in such SPI data telegrams to theprocessor. In this context, advantageously, the interface module isconnected to a memory which temporarily stores sensor data, and an alterbit makes it possible for the processor to select the current sensordata versus the preceding sensor data for transmission. Thus, the SPIdata telegrams are not only transmitted by the interface module to theprocessor, but also the other way around.

SPI (serial peripheral interface) transmission is data transmissionbetween a master, a processor and several slaves, which are theindividual components in a control device such as the interface moduleaccording to the present invention, or a firing circuit control which isused for monitoring and firing the igniters for means of restraint. TheSPI transmission is a bidirectional and synchronous transmission. FIG. 6shows an SPI line which has five individual lines. For synchronoustransmission, a timing circuit denoted as Clk is present. For datatransmission from the master to a slave there is a MOSI (master out,slave in) line, but for data transmission from a slave to the master, aMISO (master in, slave out) line is present. In order to select theappropriate slave, the CS (chip select) line is used. In order torelease the SPI data transmission, an enable line, here denoted as EN,is used. The SPI line starts at the master and then branches out to theindividual slaves, the SPI line, however, having five single lines.

FIG. 1 shows a block diagram of the device according to an exampleembodiment of the present invention. A sensor 1, for example, anacceleration sensor, or another type of peripheral sensor is connectedto a first data input of an interface module 3 via a data input. Asensor 2, for example, a pressure sensor, is connected to interfacemodule 3 via a second input of interface module 3. Interface module 3has a memory unit 4. Interface module 3 is connected to a processor 5via a first data input/output. For this an SPI line 6 is installed. SPIline 6 branches from processor 5 to an ignition drive circuit 51.Processor 5, interface module 3, SPI line 6, ignition drive circuit 51and memory 4 are elements of a control unit 7. Control unit 7 is in thiscase used for the control of restraining systems.

Interface module 3 has means for data transmission and means for signalprocessing, in order to be able to attend to the task of reformatting.For this purpose, a memory 4 is included to aid in synchronization andsequence control. Furthermore, interface module 3 has a current sourcefor supplying vehicle sensors 1 and 2 with electrical energy.

The connection to sensors 1 and 2 may also be implemented via a bus tointerface module 3. Sensors 1 and 2 transmit their sensor dataasynchronously in data telegrams to interface module 3, which takes fromthese data telegrams the useful data and reformats them into SPI datatelegrams, which are then transmitted to processor 5 via SPI line 6.Sensors 1 and 2 begin immediately with asynchronous data transmission,as soon as they are supplied with energy. In this case, the energysupply takes place via the lines of interface module 3 to sensors 1 and2. For this, direct current is used, on which the sensors then modulatetheir data. Manchester coding may be used in this instance, and aswitching back and forth takes place between two current levels. Thus,apart from the energy supply, only one unidirectional data transmissiontakes place from sensors 1 and 2 to interface module 3.

In this connection, interface module 3 temporarily stores the receivedsensor data of a data telegram in memory 4, so that the processor 5 canretrieve the current and preceding sensor data from memory 4 ininterface module 3. Thus, if a loss of the sensor occurs, processor 5can access the sensor data, which the sensor had produced before itfailed.

FIG. 2 shows the block diagram of the sequence of the device accordingto an example embodiment of the present invention. In method step 8,sensors 1 and 2 send their sensor data asynchronously in first datatelegrams to interface module 3, after they have been supplied withelectrical energy via the line over which the data telegrams are sent.Accordingly, a powerline data transmission takes place. In method step9, interface module 3 recognizes the individual data telegrams bycounting off the edges of the impulses. In this context, it is possibleto inform interface module 3 by further signals as to which sensors aresending data telegrams.

In method step 10, interface module 3 stores the sensor data in memory4, storing for each sensor 1 and 2 both the current sensor value and thepreceding sensor value. Method step 14 now checks whether the mostrecent sensor data or the preceding sensor data should be transmittedfrom memory 4 synchronously via SPI line 6 to processor 5 in SPI frames.This is recognized by whether processor 5 has set an alter bit via anSPI data telegram over the MOSI line or not. If this is the case,interface module 3 gets the newest data from memory 4 in method step 16.If not, interface module 3 gets the preceding sensor data from memory 4in method step 15.

In method step 11, reformatting of the data by interface module 3 takesplace, in that interface module 3 transmits the sensor data to the datafiles of SPI frames and may fill up the empty spaces in the SPI datafield with zeros. Processor 5 recognizes the zeros as blank information.Using the selected sensor data, in method step 12 the transmission in anSPI data telegram takes place. In method step 13, processing of thesensor data thus transmitted by processor 5 takes place, for example,whether the restraining systems are to be triggered or not. Processor 5here computes the release algorithm for the connected restrainingsystems. If the sensor data indicate a crash, then, according to theseverity of the crash, which may also be derived from the sensor data,triggering of the restraining systems takes place.

FIG. 3 illustrates a data frame which is transmitted by sensor 1 orsensor 2 to interface module 3. The data frame is made up of 13 bits,and is subdivided in the following manner: two start bits are included,marked S1 and S2, which are followed by 10 data bits, which includeacceleration data. The data bits are numbered from D0 through D9. Thedeactivation of the data frame is formed by a parity bit for theplausibility check of the data transmitted in the data telegram. A bitduration of 8 microseconds, for example, is provided here, whereas thetime t_(tran) is specified as 88 microseconds and the total time of thedata telegram t_(pas) is specified as 28 microseconds. A Manchestercoding is applied, in this context each bit duration being divided upinto two intervals of equal length. In this connection, a logical 1 isrepresented by having the current high in the first half and low in thesecond half. On the other hand, a logical 0 is transmitted by having thecurrent low at first and then high. This scheme guarantees that each bitduration has a transition in the middle, which makes synchronizing easyfor the receiver, that is, interface module 3. A better stability withregard to EMV (electromagnetic compatibility) is achieved by the currentmodulation.

FIG. 4 represents how the seven data bits of a data telegram of asensor, here of sensor 2, are transmitted to the 10 data bits of the SPIdata field. Since the SPI data field has two bits more than the 8 dataof the sensor data telegram, the first two bits are set using zeros.This is to ensure that the data telegrams of the sensors each havefewer, or at most as many data bits as the SPI data telegrams have. FIG.5 shows such a data telegram of an SPI data frame. It begins with astart bit SI which is followed by a synchronization bit 15, which is setby a 1. Bits 14 and 13 form a channel address, while bit 12 is the alterbit. The alter bit is set here as 0, and it means that the sensor isrequesting the newest sensor value from interface module 3. Bits 11 and10 are additional formatting data, upon which there follow the 10 databits which have the actual sensor data.

What is claimed is:
 1. A device for transmitting data between vehiclesensors and a control unit, comprising: an interface module configuredto decode a first data telegram having sensor data transmittedasynchronously from a first one of the vehicle sensors, and reformat thefirst data telegram into a second data telegram, the interface modulefurther configured to synchronously transmit the second data telegram toa processor of the control unit.
 2. The device of claim 1, wherein theinterface module is further configured to copy the sensor data of thefirst data telegram into a data field of the second data telegram andsupplement missing data.
 3. The device of claim 1, wherein the interfacemodule includes a memory unit configured to temporarily store the firstsensor data, and wherein the second data telegram has an alter bit, thememory unit including a first data field for old field sensor data and asecond data field for new sensor data, the processor setting the alterbit to select between the old sensor data and the new sensor data. 4.The device of claim 1, wherein the interface module is configured toreceive the first data telegram in 13-bit data frames having edges, andthe interface module is configured to count out the edges in order torecognize the first data telegram.
 5. The device of claim 1, wherein theinterface module supplies the vehicle sensors with electrical energy. 6.The device of claim 1, wherein the first one of the vehicle sensors isconfigured to create the first data telegram by a current modulation. 7.The device of claim 1, wherein the first one of the vehicle sensors isconfigured to code the first data telegram using Manchester coding.